Pump assembly for a fuel cell system

ABSTRACT

A pump assembly including a first subassembly and a second subassembly. The first subassembly includes a fluid conduit; an inlet fluidly coupled to the liquid reactant dispenser and the fluid conduit; an outlet fluidly coupled to a reaction chamber and the fluid conduit; and a diaphragm, defining a portion of the fluid conduit, that flexes to pump the liquid reactant from the inlet to the outlet. The diaphragm preferably includes an actuation point coupled to the diaphragm, wherein the liquid reactant is substantially contained within the first subassembly during pumping. The second subassembly is couplable to the first subassembly, and is fluidly isolated from the liquid reactant. The second subassembly includes an actuator that couples to the actuation point, wherein operation of the actuator causes pumping action.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of prior application Ser. No.11/203,001, filed on 11 Aug. 2005, which is incorporated in its entiretyby this reference.

This application claims the benefit of U.S. Provisional Application No.61/408,462, filed on 29 Oct. 2010, which is also incorporated in itsentirety by this reference.

FIELD OF THE INVENTION

This invention relates generally to the fuel cell field, and morespecifically to a pump assembly for a fuel cell system.

BACKGROUND

Modern portable electronic devices are demanding increasing amounts ofelectrical power and chemical batteries are often the performancebottleneck for such devices. Wireless products, such as personal digitalassistants, mobile phones, entertainment devices, and next generationlaptops in particular have a great demand for sustained power. Forlong-term portable operations, fuel cells are an attractive solution.Fuel cells, like batteries, efficiently convert chemical energy intoelectricity, but have additional advantages, such as higher energydensity and the capability for instant refueling. Fuel cells aretypically fuelled by hydrogen gas, but there are technologicalchallenges in storing and delivering hydrogen gas to the fuel cells in acost effective and efficient manner. One particular challenge is toprovide a fuel supply that is inexpensive, safe, light and compactenough to be readily portable yet store enough hydrogen to provide auseful amount of fuel to the fuel cell. State of the art means forstoring hydrogen include metal hydride canisters to store hydrogen atrelatively low pressures, and pressure tanks to store compressedhydrogen at elevated pressures. Both approaches have drawbacks; forexample, metal hydride storage is relatively safe but has a low energydensity to weight ratio, and compressed hydrogen may have a high energydensity to weight ratio but requires high strength and expensivecontainment solutions.

Other efforts have been directed at generating hydrogen gas from ahydrogen-containing fuel precursor such as sodium borohydride. In suchapproaches, the fuel solution is exposed to a reactant to facilitate theproduction of hydrogen gas. This reactant is typically a liquid reactantthat must be pumped to a reaction site. In conventional systems, thepump is either be placed within the fuel generator or within the fuelcell system. Placement of the pump within fuel generator allows for asimple fluid interface, requiring only a fuel outlet, but also increasesthe cost of the fuel generator, which is typically a disposablecomponent and thus, cost sensitive. Placement of the pump within thefuel cell system decreases the cost of the fuel generator, but adds thetechnical complexities of managing multiple fluid ports, as the liquidreactant must be pumped into the fuel cell system and back into the fuelgenerator.

Therefore, there exists a need for a better pump assembly in the fuelcell system to pump liquid reactant to the reaction site. Morespecifically, there exists a need for a pump assembly that splits thepump actuator from the fluid-contacting components, effectivelydecreasing the cost of fuel generator while minimizing the technicalcomplexities of the system arising from multiple fluid ports.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic representation of the pump assembly.

FIG. 2 is a schematic representation of a fuel generator incorporatingthe first subassembly of the pump assembly.

FIG. 3 is a schematic representation of a fuel cell stack incorporatingthe second subassembly 300 of the pump assembly.

FIG. 4 is a schematic representation of the first subassembly.

FIG. 5 is a schematic representation of the second subassembly 300.

FIGS. 6A and 6B are schematic representations of the first subassemblywith a first embodiment of an auxiliary component, wherein the diaphragmis in an unflexed state and a flexed state, respectively.

FIGS. 7A and 7B are schematic representations of the first subassemblywith a first embodiment of an auxiliary component including a returnelement, wherein the diaphragm is in an unflexed state and a flexedstate, respectively.

FIG. 8 is a schematic representation of the first subassembly with asecond embodiment of an auxiliary component.

FIGS. 9A, 9B, 9C, and 9D are schematic representations of: the firstsubassembly with a third embodiment of an auxiliary component; the thirdembodiment of the auxiliary component further including a positionretention mechanism; the third embodiment further including a returnelement in its relaxed state; and the third embodiment further includinga return element in its compressed state, respectively.

FIGS. 10A and 10B are schematic representations of the first subassembly(bottom) coupled to the second subassembly 300 (top), wherein the secondsubassembly 300 includes a first embodiment of a linear actuator, shownin a retracted state and an extended state, respectively.

FIGS. 11A and 11B are schematic representations of the first subassembly(bottom) coupled to the second subassembly 300 (top), wherein the secondsubassembly 300 includes a second embodiment of a linear actuator, shownin a retracted state and an extended state, respectively.

FIGS. 12A and 12B are schematic representations of the first subassembly(bottom) coupled to the second subassembly 300 (top), wherein the secondsubassembly 300 includes a variation of the second embodiment of alinear actuator, shown in a retracted state and an extended state,respectively.

FIGS. 13A and 13B are schematic representations of the first subassembly(bottom) coupled to the second subassembly 300 (top), wherein the secondsubassembly 300 includes a third embodiment of a linear actuator, shownin a retracted state and an extended state, respectively.

FIGS. 14A and 14B are schematic representations of the first subassembly(bottom) coupled to the second subassembly 300 (top), wherein the secondsubassembly 300 includes a fourth embodiment of a linear actuator, shownin a retracted state and an extended state, respectively.

FIGS. 15A and 15B are schematic representations of the first subassembly(bottom) coupled to the second subassembly 300 (top), wherein the secondsubassembly 300 includes a fifth embodiment of a linear actuator, shownin a retracted state and an extended state, respectively.

FIGS. 16A and 16B are schematic representations of the first subassembly(bottom) coupled to the second subassembly 300 (top), wherein the secondsubassembly 300 includes a sixth embodiment of a linear actuator, shownin a retracted state and an extended state, respectively.

FIGS. 17A and 17B are schematic representations of the first subassembly(bottom) coupled to the second subassembly 300 (top), wherein the secondsubassembly 300 includes a seventh embodiment of a linear actuator,shown in a retracted state and an extended state, respectively.

FIG. 18 is a schematic representation of the first subassembly (bottom)coupled to the second subassembly 300 (top), wherein the secondsubassembly 300 includes a first embodiment of a rotational actuator,shown in a coupled state.

FIGS. 19A and 19B are schematic representations of the first subassembly(bottom) coupled to the second subassembly 300 (top), wherein the secondsubassembly 300 includes a second embodiment of a rotational actuator,shown in an uncoupled state and a coupled state, respectively.

FIGS. 20A and 20B are schematic representations of the first subassembly(bottom) coupled to the second subassembly 300 (top), wherein the secondsubassembly 300 includes a first embodiment of an electromagneticactuator, shown in a retracted state and an extended state,respectively.

FIGS. 21A and 21B are schematic representations of the first subassembly(bottom) coupled to the second subassembly 300 (top), wherein the secondsubassembly 300 includes a second embodiment of an electromagneticactuator, shown in a retracted state and an extended state,respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiments of the inventionis not intended to limit the invention to these preferred embodiments,but rather to enable any person skilled in the art to make and use thisinvention.

As shown in FIG. 1, the pump assembly of the present invention includesa first subassembly 200 that pumps a liquid reactant from a liquidreactant dispenser to a reaction chamber, and a second subassembly 300that induces pumping within the first subassembly 200, wherein the firstsubassembly substantially isolates the liquid reactant from the secondsubassembly 300. The pump assembly is preferably incorporated into afuel cell system 100 including a fuel generator 120 and a fuel cellarrangement 140, and is preferably used to move a liquid reactant 244within the fuel generator 120 without exposing the liquid reactant 244to other system components. In other words, the liquid reactant 244 ispreferably isolated within the fuel generator 120 throughout the entirepumping process. This is preferably accomplished by isolating thefluid-contacting components within a first subassembly 200 and byisolating all other components (particularly the actuating components)of the pump within a second subassembly 300, wherein the firstsubassembly 200 is incorporated within the fuel generator 120 and thesecond subassembly 300 is incorporated within the fuel cell arrangement140. In doing so, the pump assembly of the present invention may presentseveral advantages. First, by isolating the fluid-contacting componentswithin the first subassembly 200, the fuel generator 120 (whichincorporates the first subassembly 200) may be made at a substantiallylow enough cost to be a single use disposable product. Secondly, byretaining the reactants entirely within the first subassembly 200 (andtherefore the fuel generator 120), chances of leakage and subsequentdamage to a user or surrounding equipment may be reduced. The pumpassembly preferably forms a positive displacement pump, but mayalternatively include an axial flow pump, a gravity pump, anelectro-osmosis pump, or any other pump wherein the fluid-contactingcomponents may be isolated from the actuating components.

The fuel cell system 100 that utilizes the pump assembly preferablyincludes a fuel generator 120 and a fuel cell arrangement 140. The fuelcell system 100 is preferably a hydrogen fuel cell system 100, but mayalternatively be any other system that converts a fuel into electricity.Likewise, as shown in FIG. 3, the fuel cell arrangement 140 ispreferably any fuel cell arrangement (with one or more fuel cellsarranged in a stack, in series, in parallel, etc.) that convertshydrogen gas to electricity, but may alternatively convert any othertype of fuel to electricity. Similarly, the fuel generator 120 ispreferably a hydrogen generator (e.g. a sodium borohydride hydrogengenerator or an aluminum hydride hydrogen generator), but mayalternatively be any other fuel generator 120. As shown in FIG. 2, thefuel generator 120 preferably contains a liquid reactant 244, containedin a liquid storage area, and a solid reactant, contained in a reactionarea, wherein the liquid reactant 244 is pumped to the reaction area toreact with the solid reactant and produce hydrogen gas and wasteproducts, which are passed through a product collection area 122 thatfilters out the hydrogen gas. The liquid reactant 244 is preferably anacid solution (e.g. citric acid or sulfuric acid), more preferably adiluted acid-water solution, but may alternatively be an anti-freezesolution (ethylene glycol, propyl glycol), combination thereof, orwater. The solid reactant preferably includes sodium borohydride, butmay alternatively include aluminum hydride or any suitable hydrogenstorage material that reacts to produce hydrogen. By using the pumpassembly of the present invention, substantially all fluid except thefuel (e.g. H₂ gas) should be contained inside the fuel generator 120 atall times during the operation of the fuel generator 120. The fuel ispreferably the only fluid allowed to flow out of the fuel generator 120,and preferably substantially flows into the fuel cell arrangement 140from an outlet 124 in the fuel generator 120 to an inlet 144 in the fuelcell arrangement 140, wherein the fuel generator 120 outlet 124 and fuelcell inlet 144 are fluidly coupled.

The First Subassembly

As shown in FIG. 4, the first subassembly 200 of the pump includes aninlet 240, an outlet 260, a fluid conduit 210, a diaphragm 220, and anactuation point 280. The first subassembly 200 functions to pump aliquid reactant 244 from a liquid reactant storage area 242 to areaction area containing a second reactant. The first subassembly 200 ispreferably incorporated into a hydrogen generator (e.g. a sodiumborohydride or aluminum hydride system), but may alternatively beincorporated into or removably coupled to any fuel generator 120.Furthermore, the first subassembly 200 functions to isolate the liquidreactant 244 within the hydrogen generator, wherein the pumped liquidreactant 244 is substantially retained within the hydrogen generatorduring the pumping process.

The inlet 240 of the first subassembly 200 functions to fluidly couplethe fluid conduit 210 to the liquid reactant 244 in the liquid reactantstorage area 242. The inlet 240 is preferably a portion of a tube 246located within the liquid reactant storage area 242, but mayalternatively be a wick or membrane fluidly coupled to a liquid reactantstorage area outlet 260. The inlet 240 preferably includes a passive,one-way valve 248 that allows fluid flow out of the liquid reactantstorage area 242 and prevents fluid flow into the liquid reactantstorage area 242. However, the inlet 240 may alternately include anactive one-way valve, an active two-way valve, or no valves at all. Thefirst subassembly preferably includes one inlet 240, but mayalternatively include any suitable number of inlets.

The outlet 260 of the first subassembly 200 functions to fluidly couplethe fluid conduit 210 to the reaction area and to transfer liquidreactant 244 from the first subassembly 200 to the reaction area. Theoutlet 260 is preferably a nozzle 266 located within the reaction area262 proximal to the solid reactant, but may alternatively be a tube orwick fluidly coupled to the inlet 240 of the reaction area. The outlet260 preferably includes a passive, one-way valve 264 that allows fluidflow out of the first subassembly 200 and prevents fluid flow into thefirst subassembly 200. However, the outlet 260 may alternately includean active one-way valve, an active two-way valve, or no valves at all.The first subassembly preferably includes one outlet, but mayalternatively include two outlets, three outlets, or any number ofoutlets, wherein the additional outlets may be disposed in the reactionarea or in other areas of the fuel generator 120 (e.g. a productcollection area or the outlet of the reaction area).

The fluid conduit 210 of the first subassembly functions to contain thepacket of liquid reactant being pumped, and may cooperate with thediaphragm to generate the pumping pressures. The fluid conduit 210 ispreferably a pumping chamber, but may alternatively be a tube. The fluidconduit 210 is fluidly coupled to the diaphragm, the inlet(s) and theoutlet(s). The diaphragm preferably defines a portion of the fluidconduit 210, more preferably a wall of the fluid conduit 210. The inletand outlet are preferably positioned on opposing sides of the fluidconduit 210, but may alternatively be positioned in any suitableposition. In one specific embodiment, the fluid conduit 210 is asubstantially rigid prismatic pumping chamber, wherein the diaphragmforms the chamber wall most proximal to the first subassembly exterior,the inlet is located on a wall adjacent the diaphragm, and the outlet islocated on a wall opposing the inlet. In a second specific embodiment,the fluid conduit 210 is a substantially flexible tube, wherein thediaphragm is a longitudinal portion of the tube and the first and secondends of the tube form the inlet and outlet, respectively. The firstsubassembly 200 preferably includes one fluid conduit 210, but mayalternatively include any suitable number of fluid conduit 210 s.

The diaphragm 220 of the first subassembly 200 functions to pump apacket of liquid reactant 244 from the inlet 240 to the outlet 260through the fluid conduit 210. The diaphragm 220 is preferably fluidlycoupled to the fluid conduit 210, the inlet 240, and the outlet 260, andis preferably located between the inlet valve and the outlet valve. Thediaphragm 220 is preferably disposed near the exterior of the firstsubassembly 200, more preferably near the exterior of the fuel generator120. However, the diaphragm 220 may alternately be disposed toward theinterior of the first subassembly 200. The diaphragm 220 preferablyincludes a piece of flexible material 222 fluidly coupled to fluidconduit 210, wherein flexion of the diaphragm 220 toward the interior ofthe fluid conduit 210 (flexed state) creates a positive pressure thatforces any liquid reactant 244 contained within the fluid conduit 210through the outlet (preferably the outlet valve), and relaxation of thediaphragm 220 (unflexed state) creates a negative pressure that pullsliquid reactant 244 through the inlet (preferably the inlet valve) intothe fluid conduit 210. Alternately, the diaphragm 220 may include apiece of flexible material 222 fluidly coupled to the fluid conduit 210,wherein flexion of the diaphragm 220 toward the exterior of the firstsubassembly 200 creates a negative pressure that pulls liquid reactant244 through the inlet valve and relaxation or flexion of the diaphragm220 toward the interior of the first subassembly 200 pushes liquidreactant 244 through the outlet valve. The diaphragm 220 may alsoinclude a section of flexible tubing 224, wherein the tubing fluidlycouples the inlet 240 to the outlet 260. In this case, the diaphragm 220may move packets of liquid reactant 244 by being periodically radiallyoccluded, wherein the radial occlusion moves to push liquid reactant 244out of the outlet 260 and pull liquid reactant 244 in through the inlet240 (e.g. via peristaltic pumping). The radial occlusion is preferablyaccomplished by flexing a portion of the diaphragm 220 toward theopposing wall of the diaphragm 220. Reciprocation of the diaphragm 220is preferably achieved by repeated flexion of the diaphragm 220.However, the diaphragm may alternatively be a substantially rigidconduit (e.g. a porous material, capillary tube, membrane, microchannel,etc.), wherein the diaphragm facilitates the movement of liquid reactantthrough the diaphragm when a voltage is applied across the diaphragm,preferably to the inlet and outlet (e.g. via electro-osmosis). Thediaphragm 220 is preferably made from a polymer, and more preferably apolymer with a high melting temperature to withstand the hightemperatures generated by the liquid- and solid-reactant reaction. Thediaphragm 220 may additionally or alternatively include metal, such as ametal sheet or metal lining. Examples of materials that the diaphragm220 may be made of include silicone rubber, polyethylene, PVC, PEEK,PTFE, aluminum, copper, cobalt, nitinol, magnetite, etc.

The actuation point 280 of the first subassembly 200 functions to couplewith the second subassembly 300 to facilitate liquid reactant pumpingfrom the inlet 240 to the outlet 260. The actuation point 280 ispreferably positioned on the diaphragm 220, and more preferably forms aportion of the diaphragm, such that components of the second subassembly300 directly contact the diaphragm 220. However, the actuation point 280may alternatively be located on an auxiliary component 290, containedwithin the first subassembly 200, wherein the second subassembly 300actuates the auxiliary component 290, which actuates the diaphragm 220.The auxiliary component 290 may additionally include a return element292 that returns the auxiliary component 290 to a resting position thatallows the diaphragm 220 to be in an unflexed state.

In a first embodiment of the auxiliary component 290 (shown in FIGS. 6Aand 6B), the auxiliary component 290 is preferably a rod slidablycoupled to both the diaphragm 220 and the exterior of the firstsubassembly 200, more preferably to the exterior of the fuel generator120, wherein the actuation point 280 is on the end of the rod distal tothe diaphragm 220, such that the second subassembly 300 linearlyactuates the rod to extend and retract, flexing and unflexing thediaphragm 220, respectively. The rod preferably further includes aspring as a return element 292, allowing the rod to retract back to aresting position (as shown in FIGS. 7A and 7B). In a first embodiment,the rod is preferably mechanically coupled to the diaphragm 220 and thesecond subassembly 300, such that a force applied against the rod by thesecond subassembly 300 translates to a force that flexes the diaphragm220. However, the rod may also be magnetically coupled to the secondsubassembly 300 and mechanically coupled to the diaphragm 220, wherein achange in the magnetic field of the second assembly results in lineartranslation of the rod against the diaphragm 220, flexing the diaphragm.

In a second embodiment, as shown in FIG. 8, the auxiliary component 290may alternately not include a rod at all, but be a piece of magneticmaterial 291 coupled to the diaphragm 220 such that changes in amagnetic field applied by the second subassembly 300 results in movementof the diaphragm 220 as the magnetic material responds to the changes.In this embodiment, the elasticity of the diaphragm 220 is preferablythe return element 292, but a spring or set of springs may also bedisposed on the diaphragm 220 to cause it to return to an unflexed statewhen not in operation.

In a third embodiment, as shown in FIG. 9, the auxiliary component 290may alternately be a rotor 294, wherein the actuation point 280 issubstantially in the center of the rotor 294 end face and the diaphragm220 is slidably disposed about a portion of the rotor circumference 296,such that the diaphragm 220 substantially contacts the portion of therotor circumference for a majority of the operation time. A separateactuator, contained within the fuel cell system, preferably actuates therotor 294. In this embodiment of the auxiliary component 290, the rotor294 preferably includes one or more rollers 297 disposed on the exteriorof the rotor about the rotor circumference, such that the rollers 297protrude radially from the rotor 294, wherein the rollers 297 rotatewith the rotor 294. This embodiment is preferably used with the tube 224embodiment of the diaphragm 220. When the roller 297 contacts thediaphragm 220 during the rotor rotation, the roller protrusion 297pushes against the portion of the diaphragm 220 closest to the rotor294, thereby flexing a portion of the diaphragm to occlude the diaphragm220 (tube 224). As the rotor 294 rotates, the protrusion and occlusionmove with the rotor 294, effectively pushing any fluid ahead of theocclusion in the direction of rotor rotation. As shown in FIG. 9B, thisembodiment may additionally include a position retention (e.g.ratcheting mechanism) that allows only rotation away from the liquidreactant storage area 242, preventing backward rotation caused bypressure generated by the reaction between the liquid- andsolid-reactants. This embodiment may additionally include a returnelement 292 that removes the couple between the rotor 294 and thediaphragm 220 when not coupled to the second subassembly 300. As shownin FIGS. 9C and 9D, an example of such a return mechanism is a set ofsprings coupled to the interior rotor end face (the rotor 294 end facefurthest from the exterior of the first subassembly 200). These springsare preferably soft enough to be easily compressed when the firstsubassembly 200 is coupled to the second subassembly 300, but are stiffenough to push the rotor 294 out of the operative plane of rotation whenthe first subassembly 200 is decoupled from the second subassembly 300,effectively removing the couple between the rotor 294 and the diaphragm220 when the fuel cell system 100 is not in operation. The rotor anddiaphragm couple is preferably maintained when the fuel cell system 100is not in operation. However, in a variation of this embodiment (shownin FIG. 18) both rotor 294 and the roller protrusion are part of thesecond assembly, effectively removing the coupling between the rotor andthe diaphragm 220 when the fuel cell system 100 is not in operation.

In a fourth embodiment, as shown in FIG. 19A, the auxiliary component290 is a concave groove 298 disposed on the side of the diaphragm 220most interior to the first subassembly 200, such that the auxiliarycomponent 290 is concave toward the exterior of the first subassembly200 and the diaphragm 220 is disposed between the auxiliary component290 and the exterior of the first subassembly 200. This auxiliarycomponent embodiment is preferably used with the tube embodiment of thediaphragm 220. In this embodiment, the entire auxiliary component 290 isthe actuation point 280, wherein a component of the second subassembly300 compresses a portion of the diaphragm 220 to occlude the diaphragmagainst the auxiliary component 290 (groove 298).

In a fifth embodiment, the auxiliary component 290 includes a pair ofelectrical contacts (electrodes) contacting the diaphragm 220, morepreferably contacting the diaphragm near the inlet 240 and outlet 260,respectively. The negative electrode is preferably located near theinlet and the positive electrode near the outlet, but the electrode pairmay have any other suitable orientation or positioning. This auxiliarycomponent 290 is preferably utilized with the electro-osmosis embodimentof the diaphragm 220. The auxiliary component preferably electricallycouples the actuator, wherein the voltage between the electrode pair isbrought to the same voltage as the actuator, effectively applying avoltage over the diaphragm 220 to pump the liquid reactant from theinlet to the outlet.

The Second Subassembly

The second subassembly 300 of the pump includes an actuator 320 thatfunctions to effect pumping within the first subassembly 200. Theactuator 320 preferably functions to actuate the flexion of thediaphragm 220, but may alternatively effect pumping in any suitablemanner. The second subassembly 300 may additionally include atranslational member, which functions to mechanically translate motionfrom the actuator 320 to the actuation point 280. The second subassembly300 is preferably incorporated into a fuel cell arrangement 140, but mayalternatively be clipped, plugged, or otherwise coupled to a fuel cell.Alternately, the second subassembly 300 may be a stand-alone componentand not be incorporated with any component of the fuel cell system 100.The fuel stack preferably converts hydrogen gas to electricity, but mayalternatively convert any other fuel to electricity.

The actuator 320 of the second subassembly 300 functions to actuate thediaphragm 220 in the first subassembly 200. This actuation is preferablyachieved after the first and second subassemblies are coupled togetherby the connector 500, and after a signal indicating the initiation offuel production (e.g. a start signal) has been received. The actuator320 is preferably a mechanical actuator, but may alternatively be ahydraulic actuator or an electrical actuator. The actuator 320 ispreferably powered electrically, wherein electricity is supplied to theactuator 320 by an auxiliary power source, such as a rechargeablebattery 400 (shown in FIG. 5). To achieve actuation of the diaphragm220, the actuator 320 preferably actuates a translational member 340,included in the second subassembly 300, that physically couples with theactuation point 280 in the first subassembly 200 to reciprocate thediaphragm 220. The actuator 320 is preferably a linear actuator 322 (asshown in FIGS. 15 and 16) that moves the translational member 340 (e.g.pump plunger 322 b) along the longitudinal axis of the plunger 322 b,but may alternatively be a rotational actuator that rotates thetranslational member 340 about the rotational axis of the translationalmember 340. The linear actuator 322 is preferably used to actuate thediaphragm 220 directly, wherein the translational member 340 extends toflex the diaphragm 220, and retracts to relax the diaphragm 220. Thetranslational member 340 preferably substantially contacts the diaphragm220 throughout the pumping cycle, but may alternatively only contact thediaphragm 220 when flexing the diaphragm 220. The linear actuator 322may also be used with the rod embodiment of the auxiliary component 290,wherein the translational member 340 couples to the end of the roddistal from the diaphragm 220 (actuation point). The rotational actuatoris preferably used with the rotor embodiment of the auxiliary component290, wherein the translational member 340 couples with the rotating axisof the rotor (the auxiliary component) at the actuation point 286, orwith the grooved embodiment 298 of the auxiliary component 290, whereinthe translational member 340 couples with the groove 288. Thetranslational member 340 is preferably capable of extending past theexterior of the second subassembly 300, and is preferably a rod 342 withactuation point-coupling features (e.g. hooks, an asymmetric endprofile, or a plunger 322 b), but may alternatively be a rotor withrollers, a rod attached to a magnet, or include any feature that assistsin the actuation of the translational member 340 by the actuator 320.The actuator 320 may alternatively directly actuate the diaphragm 220 bycoupling electromagnetically with the actuation point 280, without theuse of a translational member 340, or may be electrical couples(electrodes) held at a predetermined voltage, wherein the actuatorcouples to the electrode pair (auxiliary component) of the firstsubassembly (e.g. the fifth embodiment). The actuator may alternativelybe any suitable actuator that interacts with the first subassembly toinduce liquid reactant pumping within the first subassembly.

In a first embodiment of the linear actuator 322 (shown in FIGS. 10A and10B), actuation is achieved by contraction and extension of a shapememory alloy wire connected to a plunger 322 b head located at theproximal end of the pump plunger 322 b (the translational member 340),wherein the pump plunger 322 b extends to push against the actuationpoint 280 of the first subassembly 200. The shape memory alloy wire isincluded of a shape memory alloy material, such as a nickel-titaniumalloy popularly known as “nitinol”. The shape memory alloy material issensitive to temperature or heat. For example, nitinol temporarilyshrinks at a range of temperatures dictated by the composition of thenitinol will expand at a relative lower temperature and return to itsoriginal condition. In response to being heated above this shrinkagetemperature, the nitinol alloy undergoes a dimensional change, such as achange in its length. In this way, the nitinol wire 322 a can undergo areduction in length and return to its original length repeatedly viarepeated temperature cycling above its shrinkage temperature and coolingto below its expansion temperature. The nitinol wire 322 a is threadedthrough the plunger 322 b head and attached at either end to the secondsubassembly 300 by crimp connections. The nitinol wire 322 a is locatedsuch that when in its contracted phase, the plunger 322 b head is in itsretracted position; when the nitinol wire 322 a is in its expandedphase, the plunger 322 b head is in its fully extended position. Thecrimp connections are connected to electrical wire that is electricallycoupled to a rechargeable battery 400.

In a second embodiment of the linear actuator 322 (shown in FIGS. 11Aand 11B), linear motion of the translational member 340 is achieved byslidably coupling the translational member 340 to the circumferentialsurface 325 of a rotating cam 324, wherein a part of the cam 324 strikesthe translational member 340 at one or more points on its circular pathto extend the translational member 340 partially out of the secondsubassembly 300. This is preferably accomplished by using a circular cam324 wherein the axis of rotation is offset from the center of the cam326, such that rotation of the cam 324 produces an ellipsoidalrotational path 327. The translational member 340 is preferably slidablyconstrained within the second subassembly 300, such that it can onlyvary between a fully extended (past the exterior of the secondsubassembly 300) and fully retracted (contained within the secondsubassembly 300) state, wherein the translational member 340 extends andretracts along its longitudinal axis. The translational member 340 iscoupled to the cam 324 such that the translational member 340 isextended past the second subassembly 300 when the rotational path of thecam reaches a vertex at the couple, and is retracted into the secondsubassembly 300 when the rotational path of the cam 324 reaches a minoraxis at the couple. Alternately, the cam itself may have an eccentricprofile that extends the translational member 340 past the exterior ofthe second subassembly 300 at a point during the cam rotation, as shownin FIGS. 12A and 12B.

In a third embodiment of the linear actuator (shown in FIGS. 13A and13B), linear motion of the translational member 340 is achieved byutilizing a linear actuator 322 including a shape memory component, morepreferably a Nitinol wire 322 a, and a rotating arm coupled to a rod342. The Nitinol wire 322 a is preferably connected to an electricalsupply and to an end of the rotating arm. The rotating arm is preferablya rigid member, wherein one end of the rotating arm is preferablycoupled to the Nitinol wire 322 a, and the other end preferably coupledto the rod 342 end at actuation point 284, preferably through the sideof the rod 342. The rotating arm preferably rotates about a pointdisposed along its length, wherein the rotation point is preferablydisposed near the center of the rotating arm length. Upon heating of theNitinol wire 322 a (preferably by running a current through the wire),the wire expands, pushing the end of the rotating arm coupled to theNitinol wire 322 a away from its equilibrium position (the position thatthe rotating arm is in when the Nitinol wire 322 a is not heated). Thismovement rotates the rotating arm about its rotation point to moveactuation point 284, thereby translating the rod 342 along the rod'slinear axis. However, since the force application to the rod actuationpoint 284 is not evenly distributed over the rod end (as the rotatingarm is coupled from one side of the rod 342), the second assemblypreferably further includes a guide that constrains the rod to move onlyalong its linear axis.

The linear actuator 322 may additionally or alternatively be apiezoelectric driver (shown in FIGS. 14A and 14B), a rack and pinion(wherein the actuator 320 drives the pinion, and the translationalmember 340 is the rack), a lead screw (shown in FIGS. 15A and 15B), aworm-gear (shown in FIGS. 16A and 16B), a belt drive, a two-bar linkagecoupled to a cam (shown in FIGS. 17A and 17B), or any other type ofactuator 320 that can extend and retract a translational member 340along its longitudinal axis. Additionally, the translational member 340may have additional physical properties, such as magnetic properties orpiezoelectric properties. For example, in an eighth embodiment of thelinear actuator 322, a stepper motor is coupled to a translationalmember 340 with a magnet at the distal end (i.e. end not coupled to thestepper motor). This embodiment is preferably used with an embodiment ofthe first subassembly 200 that incorporates magnetic elements (e.g. thediaphragm 220 incorporating a magnetic metal sheet), wherein themagnetic element of the diaphragm 220 is repelled by the translationalmember 340 such that extension of the translational member 340 repelsthe diaphragm 220, causing it to flex.

In a first embodiment of the rotational actuator (shown in FIGS. 18A and18B), rotational motion of the translational member is achieved bycoupling the translational member to a rotating motor, such as a drillmotor, a DC motor, or an AC motor. In this embodiment, the translationalmember is preferably a rod, and is preferably coupled to the actuatorsuch that rotation of the actuator rotates the translational memberaround the longitudinal axis of the translational member 340. Thetranslational member preferably mechanically couples to the rotationalaxis of the rotor embodiment of the auxiliary component 294 (in thefirst subassembly 200), such that rotation of the translational memberrotates the rotor 294.

In a second embodiment of the rotational actuator 320 (shown in FIGS.19A and 19B), rotational motion of the translational member is achievedby coupling the translational member to a rotating motor, such as adrill motor, a DC motor, or an AC motor. In this embodiment, thetranslational member is preferably an eccentric rotor and is preferablycoupled to the actuator 320 through the end faces of the rotor, suchthat rotation of the actuator 320 rotates the rotor in a plane parallelto the planes of the end faces. The translational member preferablycouples to the groove 298 embodiment of the auxiliary component 290,wherein the eccentric (i.e. protruding) portion of the rotor slidesalong the length of the groove 298 during a portion of the rotorrotation. Because the diaphragm 220 is preferably disposed between thegroove 298 and the exterior of the first assembly when utilizing thegroove 298 embodiment, the eccentric portion of the rotor occludes thediaphragm 220 when it couples with the groove 298, effectively occludingthe diaphragm 220 to push any fluid in the direction of rotation. Theactuator 320 preferably rotates the rotor in the direction of thereaction chamber, such that liquid reactant 244 is pushed toward thereaction chamber.

In a first embodiment of the electromagnetic actuator, the actuator is amechanism capable of producing a changing magnetic field. Morepreferably, the actuator is a mechanism that can change the direction ofa magnetic field, such as a solenoid. This actuator is preferably usedwith a magnetic embodiment of the first subassembly 200 (e.g. thediaphragm 220 incorporating a magnetic sheet or the magnetic rodembodiment of the auxiliary component 290). The actuator 320 repels themagnetic element of the first subassembly with a first generatedelectromagnetic field, and attracts the magnetic element with a secondgenerated electromagnetic field, wherein the first and secondelectromagnetic fields are opposing magnetic fields. Cycling between thefirst and second electromagnetic fields results in reciprocation of thediaphragm 220.

In a second embodiment of the electromagnetic actuator, the actuator isa mechanism capable of producing a changing magnetic field. Morespecifically, the actuator is a mechanism capable of changing themagnitude of the magnetic field. This actuator is preferably used with amagnetic embodiment of the first subassembly 200 (e.g. the diaphragm 220incorporating a magnetic sheet 294 or the magnetic rod embodiment of theauxiliary component 290) further incorporating a return element 292 thatallows return of the diaphragm 220 to an equilibrium position (e.g. theelasticity of the diaphragm 220, a spring coupled to the magnetic rod).The actuator 320 either repels or attracts the magnetic element of thefirst subassembly 200 with a first generated electromagnetic field, thenlowers the magnitude of the generated field to a second generatedelectromagnetic field to allow the return element 292 to return thediaphragm 220 to the equilibrium position. Cycling the generated fieldbetween a strong and weak field results in reciprocation of thediaphragm 220. Alternatively, the first and second fields may haveopposing directions, or differ in any other suitable parameter.

As a person skilled in the art will recognize from the previous detaileddescription and from the figures and claims, modifications and changescan be made to the preferred embodiments of the invention withoutdeparting from the scope of this invention defined in the followingclaims.

The Connector

The connector 500 of the pump assembly functions to removably couple thefirst subassembly 200 to the second subassembly 300. The connector 500preferably utilizes a magnetic couple, wherein the second subassembly300 includes a magnet that is magnetically attracted to a metal plateincluded within the first subassembly 200. However, the connector 500may alternately be a mechanical couple, wherein the first subassembly200 includes a protrusion that slides into and removably clips into agroove in the second subassembly 300 (e.g. a tongue and groove joint).Other examples of mechanical couples include hooks, clips, adherent,screws, or any other suitable couple that removably couples the firstsubassembly 200 to the second subassembly 300.

As a person skilled in the art will recognize from the previous detaileddescription and from the figures and claims, modifications and changescan be made to the preferred embodiments of the invention withoutdeparting from the scope of this invention defined in the followingclaims.

1-18. (canceled)
 19. A method of operating a fuel cell system, said fuelcell system comprising a fuel cartridge and a fuel cell assembly, thefuel cartridge including a liquid reactant dispenser containing a liquidreactant and a reaction chamber distinct from the liquid reactantdispenser, the fuel cell assembly including a fuel cell, the pumpassembly comprising: a first subassembly including: a fluid conduit, aninlet fluidly coupled to the liquid reactant dispenser and the fluidconduit, an outlet fluidly coupled to the reaction chamber and the fluidconduit, a diaphragm that defines a portion of the fluid conduit andthat flexes to pump the liquid reactant from the inlet to the outlet,and an actuation point coupled to the diaphragm; wherein the liquidreactant is substantially contained within the first subassembly duringpumping; and a second subassembly, couplable to the first subassemblyand fluidly isolated from the liquid reactant, the second subassemblyincluding an actuator that couples to the actuation point, whereinoperation of the actuator causes diaphragm flexion; said methodcomprising flexing the diaphragm between a flexed and unflexed state,wherein the flexed state creates a positive pressure within the fluidconduit so as to facilitate the egress of the liquid reactant from theoutlet, and the unflexed state creates a negative pressure within thefluid conduit the facilitate ingress of liquid reactant from the inlet.20. The method of claim 19, the fluid conduit comprising substantiallyrigid prismatic pumping chamber, wherein the diaphragm forms a chamberwall proximal to an exterior wall of the first subassembly, the inletbeing located on a wall adjacent to the diaphragm, and the outlet beinglocated on a wall opposing the inlet.
 21. The method of claim 20,wherein the inlet and outlet include a one-way inlet valve and outletvalve, respectively.
 22. The method of claim 19, wherein the springforce of the diaphragm transitions the diaphragm from the flexed to theunflexed state.
 23. The method of claim 19, the fluid conduit comprisinga substantially flexible tube, wherein the diaphragm is a longitudinalportion of the tube and first and second ends of the tube form the inletand outlet, respectively.
 24. The method of claim 23, the firstsubassembly further including an auxiliary component that couples theactuation point to the diaphragm, the auxiliary component being a rotor,wherein the actuation point is substantially in the center of the rotorend face and the diaphragm is slidably disposed about a portion of therotor circumference, such that the diaphragm substantially contacts theportion of the rotor circumference for a majority of the operating time,said method comprising rotating the rotor.
 25. The method of claim 20,wherein the auxiliary component comprises a concave groove disposed onthe diaphragm most interior to the first subassembly, such that theauxiliary component is concave toward the center of the exterior of thefirst subassembly and the diaphragm is disposed between the auxiliarycomponent and the exterior of the first subassembly, said methodcomprising compressing a portion of the diaphragm to occlude thediaphragm against the concave groove.
 26. The method of claim 19, thefirst subassembly further including an auxiliary component that couplesthe actuation point to the diaphragm, the auxiliary component being areciprocating rod disposed between the exterior of the first assemblyand the diaphragm, with a diaphragm end and a distal end, wherein thedistal end is the actuation point, wherein the rod transfers a forcefrom the actuator to the diaphragm.
 27. The method of claim 19, whereinthe actuator comprises a shape memory alloy.
 28. The method of claim 19,wherein actuator comprises a rotatable cam, said cam having an axis ofrotation offset from center.
 29. The method of claim 19, whereinactuator comprises a piezoelectric driver.
 30. The method of claim 19,wherein the diaphragm comprises silicone rubber, polyethylene, PVC,PEEK, PTFE, aluminum, copper, cobalt, nitinol, magnetite, or acombination thereof.
 31. The method of claim 19, wherein the secondsubassembly further includes a translating member coupled to theactuator, wherein the actuator reciprocates the translating memberbetween two states: retracted mode wherein the translating member doesnot transfer substantial force from the actuator to the diaphragm,wherein the diaphragm is in the unflexed state; and an extended modewherein the translating member transfers substantial force from theactuator to the actuation point, wherein the diaphragm is in the flexedstate; said method comprising moving the translating member between theretracted mode and the extended mode.
 32. The method of claim 31,wherein the translating member contacts the actuation point in retractedmode.
 33. The method of claim 31, wherein the translating member ismoved between the retracted mode and the extended mode by theapplication of a changing magnetic field between the second assembly andthe diaphragm, said changing magnetic field resulting in a lineartranslation against the diaphragm, flexing the diaphragm.
 34. The methodof claim 32, wherein the translating member is a pump plunger.
 35. Themethod of claim 31, wherein the actuator is a mechanical actuator. 36.The method of claim 35, wherein the actuator is a screw actuator,wherein the translating member is the screw.
 37. The method of claim 19,wherein the pump assembly further includes a coupling mechanism thatremovably couples the first subassembly to the second subassembly. 38.The method of claim 37, wherein the coupling mechanism is a tongue andgroove couple, wherein the first subassembly includes a tongue and thesecond subassembly includes a groove.